If the output is like below, then you have to install mono on your device.

The program 'mono' is currently not installed. You can install it by typing:
sudo apt-get install mono-runtime

Step 2 : To install mono execute next line in a console. Currently mono-complete has to be installed to (reason currently unknown)

sudo apt-get install mono-complete

Remark: A user has found a reduced setup that makes WG++ work. (instead of the 220MB mono-complete installation, only 32MB is needed. Not tested). Seems that the reduced setup doesn't work for all users. A report came in, that charset windows-1250 and ISO 8859-2 are not supported on the reduced setup, but on the mono-complet they are.